In the past, a number of sewing operations involving the gethering together and sewing of material, such as ruffling, pleating and shirring, were performed by hand. Today, however, for most applications, such work is done with the help of automatic machinery.
This machinery is generally an attachment having a ruffling finger which bears against the work table of the sewing machine and the fabric being sewn, and moves in a reciprocating forward-backward motion. The finger grips the fabric being sewn only when it is moving toward the needle of the machine. The gripping portion of such a ruffling finger generally comprises a series of teeth that bear against the fabric at an angle. Thus, they grip the fabric in only one direction of movement. The forward movement of the ruffling finger has the effect of advancing material into the sewing machine at a greater than normal rate thus causing the machine to sew an extra amount of fabric, with the fabric lying over itself. The configuration that the fabric takes depends upon the frequency with which the ruffling finger reciprocates. For example, if the ruffling finger reciprocates once per stitch, a ruffle will result. If the finger reciprocates once for a number of stitches, a pleat will result from its reciprocating motion. We shall use the word "ruffling" and "ruffle" for the sake of convenience in referring to all operations involving the gathering together and sewing of material into a ruffle-like or pleat-like configuration.
Generally, prior art ruffling attachments achieve a reciprocating ruffling finger motion by mounting the finger on a bar which extends the length of the sewing machine and is rotatably mounted above the work table, extending between the needle end of the machine and the end of the machine on which is mounted the wheel by which the machine is driven. A lever arm extending at a right angle from the bar is secured to the bar at the end adjacent the drive wheel of the machine. A drive bar is rotatably mounted at both its ends, on one end to the end of the lever arm and on the other end to the drive wheel at a point on the wheel that is displaced from its axis of rotation. Rotary motion of the drive wheel thus results in imparting a reciprocating rotary motion to the bar to which the ruffling finger is attached. This reciprocating rotary motion, in turn, gives the ruffling finger a reciprocating motion.
With the increasing popularity of high-speed sewing machines, however, such automatic rufflers are increasingly becomming the weak link in an otherwise very time-efficient operation.
Due to the length, flexibilty, number and weight of the parts of such prior art rufflers and the fact that these parts are subjected to reciprocating motion, they are unable to function at high speeds. For the same reasons they are also especially prone to becomming damaged or worn. It is the object of the present invention to provide a high-speed ruffling attachment for a sewing machine that is capable of reliable and trouble-free operation at high speeds.